Perhaps because they saw Bambi at an impressionable age, those in the generation of American artists born since the late 1960s are marked by a terror of sentimentality. Independent movies from the US - Paul Thomas Anderson's Magnolia , Todd Solondz's Happiness, Wes Anderson's The Royal Tenenbaums - approach terrible events with a cool, jokey tone and ironic viewpoints.

In books, Jeffrey Eugenides's The Virgin Suicides treats a quintet of child deaths in one family as social comedy. Dave Eggers's A Heartbreaking Work Of Staggering Genius, which deals with the loss of both the author's parents from cancer and his subsequent guardianship of a young brother, tells of tragedy with the voice of a stand-up comic and the graphic flourishes of a cartoonist.

So the work which has made its 24-year-old author the new star of Manhattan letters - vast advance, glossy-mag biogs, translation sales - isn't the first car on this road. But it dares to take the scenic-facetious route towards the Holocaust.

In Everything Is Illuminated, a young American with the same name as the author travels to the Ukraine, carrying a photograph of the woman believed in the legends of the Safran Foer family to have saved his grandad from the Nazis. This sensitive quest is redirected as farce when Jonathan's guides in Odessa prove to be an ancient chauffeur, somewhat worryingly accompanied by a guide-dog, and the driver's grandson, Alex, a would-be translator whose ear for American is as reliable as his grandfather's eye for the road. A Jewish vegetarian, the American struggles in a country filled (as Safran Foer presents it) with meat-eating anti-semites.

Alex's imperfect English - in letters to Jonathan and sections of a novel based on the journey - form two of the book's three narrative strands. Don't try to read them at night while someone else is sleeping unless your relationship can survive frequent wakings by deranged laughter. The trick is that the translator, using a thesaurus to enrich his vocabulary, sees no distinction between common, demotic and poetic words. Or, as Alex puts it: "I fatigued the thesaurus you presented me, as you counseled me to, when my words appeared petite, or not befitting." Finding translation so "rigid", Alex "rotated" instead of "turned". The firm breasts of his fantasy woman are described as an "unmalleable bosom". The guide dog is a "Seeing Eye bitch". Hearing his little brother crying in his sleep, Alex tries to "counterfeit that I am reposing".

This technique might easily be dismissed as Benny Hill goes to Harvard - laughing at the mangling of a second language - but Alex gathers dignity with every page. Safran Foer is transmitting linguistically a message that lesser writers might have conveyed editorially: the unreliability of reconstructing foreign events. What Alex might call his fabric-lughole for English represents and echoes Safran Foer's distance from the history he is trying to see. In this way, the mistranslation tactic recalls Kurt Vonnegut's Slaughterhouse-5, in which another terrible family memory from the second world war - the bombing of Dresden - is approached, with similarly brilliant obliqueness, through science fiction.

Requiring the reader to become a translator - stopping to guess the word that Alex should have chosen - the off-centre sentences also make standard observations affectingly fresh, as when Alex notices that Jonathan is weeping: "I observed that the hero had small rivers descending his face, and I wanted to put my hand on his face, to be architecture for him." Finding new ways to describe crying might be a summary of the project of writers such as Safran Foer, Eggers and Eugenides.

The problem with high-concept framing devices in fiction is that they can make readers impatient with the more conventional sections. In the non-Alex stretches of the book, Safran Foer recreates scenes from the lives of his Ukrainian ancestors between 1791 and 1943: courtships, marriages, an accident and, eventually, salvation. Writing here in his very best American, Safran Foer never quite matches the thrill of Alex's failed English, but these sections contain some glittering observations in the style of magical realism, as when the writer imagines a bad smell "entering the mouths of the sleeping for long enough to misdirect their dreams before exiting with the next snore". Also demonstrating that the writer can target hearts as well as heads is the detail, when the characters reach Trachinbrod, of wedding rings, money and pictures buried in the earth, all these "Jewish things" interred as the Nazis advance.

Attempting to signal sincerity, Alex signs off his letters "guilelessly". Like much in this book it is a double joke, because the novel has guile by the mile. Safran Foer's American journey led from celebration in the literary pages to public sniping from some book-buyers who found it impenetrable or pretentious. But, as Alex might put it, any far-reaching reader will fornicate with this tract. They will transport it in their nerve-centres. And Foer has set himself a rigid stage performance to walk behind.